In vitro toothbrush-dentifrice abrasion of resin-modified glass ionomers.
OBJECTIVE
This study was conducted to compare the rate of abrasive wear and change in surface roughness of resin-modified and conventional acid-base glass ionomers when subjected to toothbrush-dentifrice abrasion.


METHODS
Two resin-modified and two conventional glass ionomers were used. Samples of a high-copper amalgam and a hybrid resin composite were used as reference materials. Specimens of each material were prepared and subjected to toothbrush-dentifrice abrasion using 20,000 strokes of brushing. The amount of vertical loss of material was determined by profilometry (Surfcom-4A, Tokyo-Seimitsu, Tokyo, Japan). The surface characteristics after abrasion were evaluated on secondary electron images by SEM, and the surface hardness (KHN) was also measured for all materials. Data were analyzed by one-way ANOVA (p < 0.05), followed by a multiple comparisons test using LSD (Least-significant difference) at a level of p < 0.05.


RESULTS
The abrasion resistance of resin-modified glass-ionomers was statistically lower for the amalgam and the resin composite reference materials. Statistically lower abrasion resistance and surface hardness were observed for the resin-modified glass ionomers than for their conventional acid-base counterparts when two forms of products from the same manufacturer were compared. SEM observations made after abrasion testing showed a significantly rougher surface for all glass ionomer materials than for the amalgam and the resin composite.


CONCLUSIONS
When comparisons were made between products from the same manufacturers, it was found that in vitro resistance to toothbrush-dentifrice abrasion of the resin-modified glass ionomers is inferior to that of the conventional acid-base glass ionomers. The lower abrasion resistance found in the resin-modified products appears to be related to their lower surface hardness.
Momoi
Y
Y
Department of Operative Dentistry, School of Dental Medicine, Tsurumi University, Yokohama, Japan. yasukoM@msn.com
Hirosaki
K
K
Kohno
A
A
McCabe
J F
JF
D000536:Aluminum Hydroxide / Q000737:chemistry; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D003723:Dental Amalgam / Q000737:chemistry; D003802:Dentifrices / Q000737:chemistry; D017276:Friction; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006244:Hardness; D008298:Maleates / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D014072:Tooth Abrasion / Q000209:etiology; D014099:Toothbrushing / Q000295:instrumentation; D015040:Zirconium / Q000737:chemistry
D003188:Composite Resins; D003722:Dental Alloys; D003802:Dentifrices; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D008298:Maleates; C081144:Photac-Fil; D019279:Resin Cements; D012117:Resins, Synthetic; C073985:Shofu Spherical alloy; C083568:Z100 composite resin; C084541:Fuji glass-ionomer lining cement; D000536:Aluminum Hydroxide; D012822:Silicon Dioxide; D003300:Copper; D003723:Dental Amalgam; C040964:Ketac-Fil; D015040:Zirconium